and
moisture. Chemical activities are augmented by tillage in setting free
plant food, promoting nutrification, hastening the decomposition of
organic matter, and the extending of these agencies to greater depth.
Tillage conserves moisture by increasing the water holding capacity of
the soil and by checking evaporation.

Of all these things which tillage accomplishes in a soil, two should
be especially emphasized for the apple orchard, namely, soil moisture
and soil texture. That moisture is a very important consideration in
the apple orchard the effects of our frequent droughts are ample
evidence. The amount of rainfall in the Eastern States when it is
properly distributed is fully sufficient for the needs of an apple
tree. By enlarging the reservoir or water holding capacity of the soil
and by preventing the loss of water by evaporation, an excess of
rainfall in the spring may be held for later distribution and use.

As a rule, the improvement of a poor soil texture is as effective as
the supplying of plant food and much cheaper. The latter is of no
consequence unless the plant can use it. Scientists tell us that there
is an abundance of plant food in most soils. The problem is to make it
available. Plant food must be in solution and in the form of a film
moisture surrounding the smallest soil particles in order to be
available to the fine plant rootlets which seek it. Good tillage
supplies these conditions. Can they be obtained equally well in
another way?

It is claimed by the advocates of the sod mulch system of orchard
culture that it also supplies these conditions. Humus or decayed
vegetable matter holds moisture. Grass or other mulch decaying in the
soil increases its humus content and hence its water holding capacity.
By forming a mulch over the soil evaporation may be checked to some
extent, although probably not as effectively in a practical way, as by
cultivation. If there is a good grass sod in the orchard, moisture and
plant food made available by that moisture are utilized, and if the
grass is allowed to go back into the soil it continues to furnish
these elements to the tree. But there is a rapid evaporation of
moisture from the surface of the leaves of grass. In fact, grass may
well serve to remove an excess of moisture in wet seasons, or from wet
lands.

Laying aside theoretical considerations, let us see what practical
experience teaches on this subject. We have the accurate data on a
large num